1. Field of the Invention
The present invention relates to a method for manufacturing a magneto-resistance effect element which is configured such that a current is flowed in the direction perpendicular to the film surface thereof to detect the magnetization of the element and the magneto-resistance effect element.
2. Description of the Related Art
Recently, the miniaturization and the high density recording of a hard disk drive (HDD) is remarkably required and being progressed. In the future, it is promised to much develop the high density recording of the HDD. The HDD of high density recording can be realized by narrowing the recording track width. However, the amplitude of the magnetization relating to the recording, that is, the recording signal may be lowered as the track width is narrowed, so that it is required that the reproducing sensitivity of the MR head for reproducing the medium signal is enhanced.
Recently, a GMR (Giant Magneto-Resistance effect) head with a high sensitive spin valve film using the GMR film is employed. The “spin valve” film has such a structure as sandwiching a non-magnetic metal spacer layer between two ferromagnetic layers. The stacking layer component structure exhibiting the change in resistance may be called as a “spin dependent scattering unit”. The magnetization of one ferromagnetic layer (often called as a “pinning layer” or “fixed magnetization layer) is fixed by the magnetization of an anti-ferromagnetic layer and the magnetization of the other ferromagnetic layer (often called as a “free layer” or “free magnetization layer”) is rotated in accordance with an external magnetic field. With the spin valve film, the intended large magneto-resistance effect can be obtained when the relative angle between the pinning layer and the free layer is changed.
A conventional spin valve film is formed as a CIP (Current In Plane)-GMR element, a CPP (Current Perpendicular to Plane)-GMR element and a TMR (Tunneling Magneto-Resistance) element. With the CIP-GMR element, a sense current is flowed along the film surface of the spin valve film. With the CPP-GMR element or the TMR element, a sense current is flowed in the direction perpendicular to the film surface thereof.
With the element which is utilized by flowing the sense current in the direction perpendicular to the film surface, the spacer layer is made of an insulating layer in the TMR element and of a metallic layer in the CPP-GMR element.
Herein, a metal CPP-GMR element of which the spin valve film is made of a metallic layer has a smaller change in resistance to render the detection of minute magnetic field difficult.
A CPP element with an oxide layer containing current confined paths in the thickness direction thereof, which is called as an “NOL (nano-oxide layer)”, is proposed (refer to Document 1). With the CPP element, both of the element resistance and the MR ratio can be increased due to the current confined to path (CCP) effect. Hereinafter, the element is called as a “CCP-CPP element”.                [Document No. 1] JP-A 2002-208744 (KOKAI)        
Such a magnetic recording device as the HDD is widely available for a personal computer, a portable music player and the like. In the future, however, the reliability of the magnetic recording device is severely required when the usage of the magnetic recording device is increased and the high density recording is also developed. It is required, for example, that the reliability of the magnetic recording device is developed under a high temperature condition or a high speed operation. In this point of view, it is desired to much develop the reliability of the magnetic head in comparison with the conventional one.
Particularly, since the CCP-CPP element has a smaller resistance than the one of the conventional TMR element, the CCP-CPP element can be applied for a high end magnetic recording device of server enterprise requiring higher transfer rate. In the use of the high end magnetic recording device, both of the high density recording and the high reliability must be satisfied. Also, the high reliability under a higher temperature condition must be preferably satisfied. In other words, the CCP-CPP element is required to be used under the more severe condition (e.g., high temperature condition) and the more severe operation (e.g., the information being read out while the magnetic disk is rotated at high speed).